Bell curve? Not just in intelligence, but in psychological factors leading to hate. If you have a billion people, the 0.1 % of its extreme nutters will be a crowd of a million.

Many propaganda accounts get closed only to have new ones with similar names created shortly after. Several dozen of those accounts might be linked to one particular person/cell/organisation...

They are only extremist from Twitter (Americentric) point of view. In other places it might well be considered a mainstream ideology.